As delegations from various minor shinobi villages arrived in Hidden Leaf Village, the village, scarred from the last great war, buzzed with life once more.
At the training grounds, Shinji, Haku, and Karin were engaged in their daily taijutsu sparring.
During a break, the three sat on a bench, wiping sweat and chatting casually.
Karin remarked offhandedly, "There've been more shinobi from other villages in the village lately."
Haku nodded. "Yeah, this morning during my training, I ran into a group from Hidden Sound Village."
"Hidden Sound Village?" Shinji raised an eyebrow.
Haku explained, "I heard it's a small shinobi village formed in recent years."
Karin added, "Even a newly established village was invited? Looks like this Ninja Alliance meeting is serious!"
Shinji fell into thought.
The Ninja Alliance meeting was shrouded in secrecy. Even as the First Chair, Shinji had no clue what was being discussed. Clearly, the Five Great Shinobi Villages were intentionally limiting who knew what to test the reliability of the smaller villages.
It was predictable that the Five Great Villages would mix truth and misinformation during the meeting, using surveillance and other methods to gauge the smaller villages' trustworthiness. After all, the last surprise attack on Hidden Rain Village had failed due to leaked intelligence, exposing their own vulnerabilities. This allowed the Akatsuki to launch successful raids on Hidden Leaf, Hidden Mist, and Hidden Waterfall Villages, even abducting Hidden Mist's Six-Tails Jinchuriki, Utakata.
Thus, rooting out spies within the Alliance was the current priority.
Based on this, Shinji was certain the Alliance wouldn't discuss anything truly critical at this stage. Eavesdropping would not only waste effort but also risk suspicion.
"Rested enough? Let's continue!" Shinji tossed aside his sweat-soaked towel and headed back to the training field.
Haku and Karin hurriedly followed.
Shinji suggested, "This time, you two team up and attack me!"
"Be careful, Shinji-kun!" Haku warned with a smile.
Shinji beckoned to Haku and Karin. "Come on!"
Without further ado, Haku and Karin launched their attack.
Shinji grinned and met them head-on.
It had been over two weeks since he successfully implanted the First Hokage's cells. During this time, he'd barely rested, sparring with Yakumo, Neji, or Kimimaro. He discovered that intense combat accelerated his body's integration with the cells.
As his fusion with the First's cells deepened, Shinji noticed not only an increase in his chakra reserves but also an improvement in the quality of his Yin Release chakra. Even his understanding of chakra nature fusion grew sharper and more profound.
Fusing different chakra natures wasn't just about mixing two types of chakra. It required transforming their properties. To achieve this, a shinobi needed exceptional control over both chakra natures involved.
Take the Third Raikage's 'Black Lightning' from Hidden Cloud or Kakashi's 'Purple Lightning' developed as the Sixth Hokage in the original timeline—both were examples of altering the properties of a single Lightning Release chakra.
In other words, mastering the property transformation of a single chakra nature was a prerequisite. Only then could two different chakra natures be fused effectively, increasing the success rate and speed of the fusion.
With this insight, Shinji stopped forcing his Yin Release and Yang Release chakra to fuse. Instead, he focused on sensing and controlling each individually, refining his mastery over Yin and Yang Release chakra.
The results were immediate.
Not only did his control over Yin and Yang Release chakra improve significantly, but the speed of their fusion within his body also increased.
"Karin took a few months after implanting the First's cells to fully achieve Yin-Yang fusion and amass enough All Creation Power to awaken the Rinnegan. At my current pace, I might be able to attempt it next month," Shinji thought, gauging his progress while sparring with Haku and Karin.
Karin's journey from implanting the First's cells to awakening the Rinnegan took roughly three months. With her as a reference and his own refinements, Shinji estimated that, if all went smoothly, he could attempt to awaken the Rinnegan in about a month and a half—a much shorter timeline than he'd initially expected.
Karin's Rinnegan awakening was already remarkably fast. As a member of the Uzumaki Clan, she could be traced to the lineage of Hagoromo's son, Asura. Thus, Shinji, as an Uchiha tied to Indra's lineage, didn't have a significant advantage over her in awakening the Rinnegan.
Moreover, when Shinji used Karin's unique chakra-healing ability to restore his blinded Mangekyo Sharingan, it effectively made her the "owner" of a restored Mangekyo Sharingan, both in bloodline and chakra nature. This made Karin a unique case, possessing the bloodlines of both Asura and Indra, despite not being their reincarnate. This gave her the highest probability of awakening the Rinnegan outside of the reincarnates themselves.
In contrast, Shinji—neither a reincarnate of Asura nor Indra and possessing only Indra's bloodline—had a lower success rate. Yet, his Yin-Yang fusion was progressing twice as fast as Karin's. This was clear evidence that the Twelve Palaces had begun unlocking his body's potential, enhancing his control over his physical form.
After the morning training session, Shinji parted ways with Haku and Karin and headed alone to Hidden Leaf Hospital.
"It seems I still can't escape needing Indra's chakra…"
Initially, Shinji thought he wouldn't need Indra's chakra. But as his Yin-Yang fusion deepened, he realized the chakra of Asura within the First's cells was noticeably stronger than his own Yin Release chakra. This meant his Yin Release was still weaker than Indra's.
So, he needed to check on Sasuke, Indra's reincarnate, to prepare for his Rinnegan awakening in a month.